has a tendency to continue to rise, seeking air of its owndensity. Consequently the column becomes unstable.From this, the rule is established that if the lapse rate ofa column of air is greater than the dry adiabatic lapserate, the column is in a state of ABSOLUTEINSTABILITY. The term absolute is used because thisapplies whether the air is dry or saturated, as isevidenced by displacing upward a saturated parcel ofair from point A along a saturation adiabat to point B.The parce1 is more unstable than if displaced along adry adiabat.STABILITY.Consider a column of dry air inwhich the actual lapse rate is less than the dry adiabaticlapse rate. The actual lapse rate is to the right of the dryadiabatic lapse rate on the Skew-T diagram (fig. 2-11).2-17AG5f0210ASATURATIONADIABATICLAPSERATEDRYADIABATICLAPSERATEACTUALLAPSERATE-10 0 10BB1POINTS B (DRY ADIABATIC) AND B (MOIST ADIABATIC)WARMER THAN SURROUNDING AIR1Figure 2-10.Absolute instability (any degree of saturation).AG5f0211-10 0 10DRY ADIABATICLAPSE RATEACTUALLAPSE RATEBPOINT B COLDER THANTHE SURROUNDING AIRAFigure 2-11.Stability (dry air).